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Title
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Glycine decarboxylase and pyruvate dehydrogenase complexes share the same dihydrolipoamide dehydrogenase in pea leaf mitochondria: evidence from mass spectrometry and primary-structure analysis.
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Authors
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J.Bourguignon,
V.Merand,
S.Rawsthorne,
E.Forest,
R.Douce.
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Ref.
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Biochem J, 1996,
313,
229-234.
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PubMed id
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Abstract
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In order to compare the dihydrolipoamide dehydrogenase associated with the
pyruvate dehydrogenase complex (E3) with that associated with the glycine
decarboxylase complex (L-protein), we report for the first time the purification
and characterization of the E3 component from pea leaf mitochondria. The first
30 amino acids of the N-terminal sequence of the mature E3 protein are identical
with those of the mature L-protein of the glycine decarboxylase complex.
Electrospray ionization-mass spectrometric analysis of E3 and the L-protein gave
exactly the same molecular mass of 49,753 +/- 5 Da. We have also confirmed the
primary structure of the L-protein, in particular the C-terminal sequence,
deduced from the cDNA published by Bourguignon, Macherel, Neuburger and Douce
[(1992) Eur. J. Biochem. 204, 865-873]. Western-blot analysis shows that
specific polyclonal antibodies raised against the L-protein recognize
specifically both E3 and L-protein but not the porcine dihydrolipoamide
dehydrogenase. We conclude that, in pea leaf mitochondria, the pyruvate
dehydrogenase and glycine decarboxylase complexes share the same
dihydrolipoamide dehydrogenase. We have also confirmed by MS analysis that the
FAD is not covalently bound to the enzyme.
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